1. Field of the Invention
The present invention relates to a die for the extrusion of hollow shapes and a method of forming an extended product, and more particularly though not exclusively, is concerned with such a die for the extrusion of materials which are difficult to solidify quickly, e.g. edible compositions such as chocolate.
2. Description of the Prior Art
We have found that the continuous extrusion of a hollow section of chocolate suffers from the problem that air can only enter the section from the downstream end of the section. When the section becomes long relative to the diameter of the hollow part, it becomes difficult for enough air to enter the section to equalize the pressure on the inside and the outside of the section. Consequently, a partial vacuum can form and if the extruded chocolate has not fully solidified, the section can collapse.
The problem is further increased if the extruded section is transversely cut after it has solidifed as the cutting blade blocks the new downstream end when the cut is first made and so prevents any air entering the section, thus causing a greater pressure difference.